This project examines the figures of Hervör and Þornbjörg from the perspective of their martial activity, attempting to break beyond the conventional binary-gender model which still continues to be widely employed in criticism regarding female characters in medieval Icelandic sagas. The last decade has seen a resurgence of scholarly interest in fornaldarsögur not only in their capacity as imaginative literary works par excellence but in their abundant deployment of supernatural content as reflections of contemporary attitudes and concerns, yet the past studies done on the two above-named saga characters have largely divorced them from the persistent supernatural undercurrents that run through these texts. It is proposed that a focus on seiðr yields a fruitful perspective on gender which situates the discourse on the latter within the magical reality of the sagas. Following a discussion of new approaches to seiðr in recent scholarship, the present inquiry into it goes beyond the stereotypically “feminine” sphere of prophesy and visions to explore its “masculine” sphere of hostile use of seiðr in battle, with attention being given to martial supernatural female beings in Old Norse sources, as well as to how the perversity and abnormality lurking within the seiðr complex affects them. The cross-dressing of both Hervör and Þornbjörg, in the context of their supernaturally-charged martial activity, forms the central focus of this project – how it alters them and how they use it to manipulate gender dynamics in their respective narratives to achieve their desired results. In their warlike aspect they cross the boundary of the norm into the territory of otherness and supernaturally potent liminal space, which empowers them but which also puts them at risk.